I have a 94 Accord 2.2 VTECH 5-speed. 268k Miles. Clutch started slipping about 3k miles ago. Took it to the dealer because they are reasonable and treat me well so at a minimum I get an estimate from them. They found low compressiin in one cylinder and really low compression in another. Rear main seal was leaking which was attributed to age and possible crankcase pressure from blow by. I let it set for 9 months because I'm busy but now I want it out of my driveway. Before I part it out I decided to try a piston soak to attempt to recover compression.

I started by using two bottles of B12 over a period of 24+ hours. After that leaked into the crankcase I cranked the motor for a few seconds and then put 4oz of MMO in each cylinder, and let it sit for 24 hours. Then I used my mytivac to suck the MMO out and inspect it. It was suprisingly clean. So I rotated the motor and put MMO back in for another 24. Sucked it out, this time it was dirtier but not black. I poured it in the oil fill. Filled up the oil with Mobil1 10w40. (Which is what I had been using for at least 100k miles due to small oil leaks and high mileage. It was the cheap stuff from WM) Took a while to get her started, had to jump it. She finally started and let it run for 1 hour.

I found leaks I didn't know I had. Plus the oil is thin from the B12 and it floats on ice so it looked worse than it was. I will refill the oil and start it again before I do another compression test. If she passes compression I will fix the oil leaks and throw a new clutch in. If not, she gets chopped. I will let you know how compression test goes.

By the way. I do not reccomend this method to anyone. I only did it because the engine had both feet in the grave already.

Okay so far, I would have used GM top engine cleaner but that another thread.

Originally Posted By: Lmelin

After that leaked into the crankcase I cranked the motor for a few seconds

That was the mistake IMO. If it just went down in the pan not a problem if you drained it but cranking it circulated throughout the engine bringing a very concentrated mix in contact with every gasket and seal.

I have a 94 Accord 2.2 VTECH 5-speed. 268k Miles. Clutch started slipping about 3k miles ago. Took it to the dealer because they are reasonable and treat me well so at a minimum I get an estimate from them. They found low compressiin in one cylinder and really low compression in another. Rear main seal was leaking which was attributed to age and possible crankcase pressure from blow by. I let it set for 9 months because I'm busy but now I want it out of my driveway. Before I part it out I decided to try a piston soak to attempt to recover compression.

I started by using two bottles of B12 over a period of 24+ hours. After that leaked into the crankcase I cranked the motor for a few seconds and then put 4oz of MMO in each cylinder, and let it sit for 24 hours. Then I used my mytivac to suck the MMO out and inspect it. It was suprisingly clean. So I rotated the motor and put MMO back in for another 24. Sucked it out, this time it was dirtier but not black. I poured it in the oil fill. Filled up the oil with Mobil1 10w40. (Which is what I had been using for at least 100k miles due to small oil leaks and high mileage. It was the cheap stuff from WM) Took a while to get her started, had to jump it. She finally started and let it run for 1 hour.

I found leaks I didn't know I had. Plus the oil is thin from the B12 and it floats on ice so it looked worse than it was. I will refill the oil and start it again before I do another compression test. If she passes compression I will fix the oil leaks and throw a new clutch in. If not, she gets chopped. I will let you know how compression test goes.

By the way. I do not reccomend this method to anyone. I only did it because the engine had both feet in the grave already.

Why would anyone consider trying to start the engine without changing the oil with the B12 in the crankcase.

Hokay soI tested the compression with the same results as before, low compression on cylinder 1 and none on cylinder 3. I did warm up the car before doing the test and this time no oil leaks, weird! At this point I figure the engine is shot, but I threw Kreen in #1 & #3 to see if that makes a difference.

Correction on earlier statement. I was using Mobile 5000 high mileage.

For what little its worth, I've stopped adding mom to my oil... unless its a fast flush like I did on my boat, but that was about 7half quarts of random oil of all weights and 2quarts of diesel. So even then I don't use it for that...

But the jug on my Harley leaks, and if I add mom to the oil (mixed for winter) it leaks a lot more,

Same with an old 305motor I have, added mmo and the rear main leaked like a mofo after 500miles... sat the truck in retirement after that one =(

Lastly, I added mmo to my 1980 th400 (the pint the bottle says)

And about 200miles later (don't drive it much ) forward seal started puking............... that one hurt me =(

But I wouldn't think twice about using it daily or dumping a quart in the new vehicle with a full tank to CLEAN THE HECK OUT OF EVERYTHING in that motor...

Maybe I had bad luck, but, who knows... there a gent at my work with a 2500hd suburban (I think that's the model) with 472xxx miles on it using mmo in the gas and oil from the day he drove it off the lot...